Just as the Anointed 144,000 (the Little Flock) are selected “out of every tribe and tongue and people and nation” (Rev 5:9 NWT), so are the Great Crowd (Rev 7:9). Neither of these two groups are the world, but they are both taken “out of” the world. This larger group (the world) from which these two classes are taken “out of” is described in Daniel 7:14, ” And to him there were given rulership and dignity and kingdom, that the peoples, national groups and languages should all serve even him. His rulership is an indefinitely lasting rulership that will not pass away, and his kingdom one that will not be brought to ruin” (NWT).
This larger group is also described as the “nations” who live in the city (Rev 21:24), yet the Great Crowd is never said to enter the city, but “…they are before the throne of God; and they are rendering him sacred service day and night in his temple;” (Rev 7:15 NWT). The Great Crowd is brought before the Jehovah’s throne for service. In contrast, the world of mankind (both raised from the dead and surviving Armageddon) are brought before the throne for judgment during the thousand year kingdom (Rev 20:12; Matt 25:31,32; Dan 7:9,10). The Great Crowd is not the world of mankind on Paradise Earth.
The evidence points to three distinct kingdom classes 1) the Anointed Little Flock of 144,000, 2) the Great Crowd and 3) the world of mankind.
The fact that both the World (Rev 22:14) and Great Crowd (Rev 7:9) are described as wearing white robes does not prove they are the same group. The Anointed 144,000 have white robes too (Rev 3:5; 19:8 –note that justification and righteousness are from same Greek root word Strong’s 1344). All who become justified have white robes, because white robes are a symbol of justification/righteousness (Isa 61:10). Anyone without a white robe (justification) has no standing with God (Matt 22:11-13). At the time of the earthly Paradise, the world will “wash” their robes (Rev 22:14 – present tense in Greek), but the Great Crowd will already have clean robes (Rev 7:14 “washed” – Greek past tense).